Hydraulic engine controlling device



June 1, 1937. E. MARTIN ET AL mnmumc ENGINE commune nnvrcn Filed May 21,1936 3 Sheets-Sheet l TOR.

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A TfTORNEY June 1, 1937. E. MARTIN er AL 2,083,946 HYDkAULIC ENGINECONTROLLING DEVICE 'Filed May 21, 1936 3 Sheets-Sheet 5 INVENTOR. .E'rlaMarla:

JabnEZnarAm/ar am BY M '9- ATTORNEY Patented June I 1, 1937 2,081,946

UNITED? STATES PATENT OFFICE HYDRAULIC ENGINE CONTROIJJNG DEVICE EricMartin, West Hartford, and John Elmer I Anderson, Portland, Conn.,assignors to United Aircraft Corporation, East Hartford, Conn., a Icorporation of Delaware Application my 21, 1936, Serial No. 81,046

' 19 Claims. (01. 60-91) 3 This invention relates to improvements inenas a radial air-cooled internal combustion engine controllingmechanisms, and has particular gine ordinarily. employed for thepropulsion of reference to a controlling mechanism for use in airplanes.It is to be understood, however, that a vehicle, such as an airplane,having one or a the device may be applied to various power plants, 5plurality of engines for controlling the speedof and the particular typeof engine illustrated in 5 the engine or engines. no way aflects thescope of the invention. The An object of the invention resides in theproengine drives a controllable pitch propeller, genvision of hydraulicmeans for manually controlerally indicated at l2, having two or moreradialling the engine'speed. ly disposed blades l4 rotatably mounted attheir A further object resides in the provision of root or base ends ina hub barrel member I6 10 manually actuatable hydraulic means of the forpitch changing movement about their loncharacter described forcontrolling the speeds of gitudinal axes. The pitch angle of the bladesall of a plurality of engines simultaneously. ll is/controlled by a pairof centrifugally actu- A still further object resides in the provisionated counterweights l8 directly connected tothe of manually actuatablehydraulic means of the respective blades and a hydraulic mechanism 15character described for synchronizing thespeeds operatively connected tothe counterweights. In of the various engines when the device is appliedthe form of propeller illustrated, the counterto an engine drivenvehicle having aplurality of weights, under the action of centrifugalforce, n i es tend to turn the blades l4 toward their high pitch Otherobjects and advantages will'be more. position, and the movable cylinder22 of the hy- 20 particularly pointed out hereinafter or will bedraulicmechanism is operative to overcome the come apparent as the descriptionproceeds. tendency of the counterweights to move the In the accompanyingdrawings, in which like blades to high pitch position, and to turn thereference numerals are used to designate similar blades to their lowpitch position. The pro- 1 25 parts throughout, there are illustratedthree peller has a limiting high pitch andlow pitch 25 slightly modifiedmechanical embodiments of position, and the pitch controlling mechanismwhat is now considered to be the preferred form is effective to maintainthe blades at any pitch of the idea of the invention. The drawings,angle between these two positions, depending however, are for thepurpose of illustration only upon the supply of hydraulic fluid to thehyand are not to be taken aslimiting the invention draulic mechanism 20.30

the scope of which is to be measured entirely by The fiuid is suppliedto the hydraulic mechathe scope of the appended claims. nism 20 throughthe bore 24 of the tubular pro- In the accompanying.- drawings, pellershaft 26 and through the hollow piston 28 Figurel is a partly schematicsectional view of upon which the cylinder 22 is reciprocably ahydraulicengine speed control mechanism conmounted, and is controlled bythe action of a 35 structed according to the idea of thisinventionspeedgcontrolling governor, generally indicated applied to an enginehaving a speed governor at 30., and particularly illustrated in Fig. 2.and a governor controlled controllable pitch pro- The governor 30 is ofthe centrifugally actupeller; v ated type, and has a pair of flyweights32 mount- Fig. 2 is a partly schematic sectional view 0! a ed upon arotatable tubular shaft 34 driven by 40 hydraulic speedregulatingmechanism similar H the engine through a suitable gear drive36. to Fig- 1 except that it is adapted for applica- These flyweights 32are operatively connected tion to a plurality of engines, the mechanismbewith a longitudinally movable valve member 38 mg shown as applied toengines each having a which controls a pair of ports 40 and 42 through'45'speed governor and driving a governor con-trolled which thehydraulic fluid is supplied to and controllable pitch propeller; drainedfrom the hydraulic propeller controlling Fig. 3 is a schematicillustration of a fourmechanism 20, the fluid being supplied to theengine airplane illustrating how the device of governor through a s'table' conduit -44 from a the invention could be applied to amulti-engine source of pressure, such as a pump (not illusvehicle; and'trated).. A similar conduit 45 leads from the 50 Fig. 4 is a partlyschematic sectional view governor to the interior of the hollowpropellersimilar to Fig. 2 showing a somewhat modified 26 throughs table011- collector rings 41. The form of engine speed controlling mechanism.action of the flyweights 32 is opposed by an ad- Reterring to thedrawings in detail, the nujustable coil spring 46 in such manner that ameral- "I generally indicates a power plant, such change of tension ofthe spring or any force ex- 55 erted upon the flyweights, in addition tothe force exerted by the spring, will tend to change the action of thegovernor and vary the speed of the engine by changing the pitch angle ofthe propeller blades l4. With one definite setting of the spring 46, theaction of the flyweights 32 will hold the valve 38 in a neutral positionwhenever the engine is operating at a certain definite speed, and willthus maintain the pitch of the propeller blades such that the propellerabsorbs the entire power output of the engine at the speed specified. Ifthe speed of the engine varies from the speed consistent with thesetting of the governor spring, the flyweights 32 will move in or outand adjust the valve 38 to either supply additional fluid to thehydraulic mechanism 28 to decrease the pitch of the propeller blades incase the engine speed goes down, or to drain some of the fluid out ofthe hydraulic mechanism and increase the pitch of the propeller bladesin case the speed of the engine goes up and, by such adjustment of theback to the speed for which the governor spring is set. As stated above,any change in the tension of the governor spring will change the speedat which the governor tends to maintain the speed of the engineconstant. Thus the speed of a single engine, or the speeds of theindividual engines of a multi-motored vehicle, can be changed oradjusted. by varying the tension or loading upon the spring of therespective engine governor.

In the particular trated in Figure 1, above t form of the inventionillusthe governor 38 is provided,

flyweights 32 and the spring 46, with a cylindrical extension 48 withinw ch is a reciprocable pisf ton 50. The piston 58 has a lapped fit withthe interior of the cylinder 48 or with a cylindrical bushing 52disposed in the cylinder to provide an oil-tight fit between the sidesof the piston and cooperating wall of the cylinder or bushing. Thepiston 58 is mounted or integrally formed upon the upper end of a stem54, the lower end of which forms an abutment 56 for the upper end of thegovernor spring 46 so that movements of the piston 58 up and down in thecylinder 48 will alter the load on the spring 46 and thus vary theaction of the centrifugal governor 30. A tubular member 58 leads fromthe space between the closed upper end of the cylinder 48 and ad-,iacent surface of the piston 58 to ahydraulic cylinder, generallyindicated'at 60. The hydraulic cylinder 60 is preferably a relativelysmall cupshaped member mounted upon the instrument board 62 of theairplane, or other vehicle, and is supplied with a manually actuatableknob 64 screw threadedand looked upon the sleeve member .66 into whichis screw threaded the end of a stem 68 which is secured at its oppositeend to a piston. 10 movable in the cylinder and having an oil-tight fitwith the interior cylinder walls to change the volume of the spacebetween the lower end of the piston and the lower closed end of thecylinder. Manual rotation of the knob 64 by screwing the stem 68 in andout moves the piston 18 to provide the change in volume and consequentchange in pressure ofthe hydraulic fluid within the cylinder 60, thecylinder 48, and the tubular connection 58 to change the loading uponthe governor spring 46. The sleeve 66 is v provided, \m'thin the cover12 on the cylinder 60, with an outwardly extending flange 14 whichunderlies ,a. recessed portion of the cover 72 and takes the thrust ofthe piston upon the screw propeller, bring the engine threaded stem 68.The stem 68 may be restrained against rotation by suitable means, suchas the washer !6, locked between the cover 12 and the upper end of thecylinder. 60 surrounding the stem 68 and provided with a tongueextending into a longitudinal groove 18 provided in the stem.

A fluid pressure gauge, generally indicated at 80, may be mounted uponthe instrument board 62 and connected with the conduit 58 by suitablemeans, such as the branch conduit 82, to indicate, by means of the hand83, the pressure exerted-by the piston 10 upon the fluid in the system.Preferably, this pressure gauge is provided with indicia 84 which arecalibrated directly in units of engine speed, such as revolutions perminute.

From the above description it will be observed that the action of thegovernor 30, and consequently the speed of the engine l0, may becontrolled by the operator of the vehicle upon which the engine ismounted by suitably controlling the manually adjustable knob 64 andthereby changing the pressure acting upon the piston 50 of the governor30.

Since many power driven vehicles, and particularly large airplanes, aredriven by a plurality of engines (usually from two to four) it isnecessary in these cases that suitable means be provided for controllingall of the engines, and such control mechanism should desirably bearranged so that all of the plurality of engines may be controlledtogether, or each engine may be controlled separately. Obviously, such acontrol for a plurality of engines could be arranged by providing eachengine-with a hydraulic control arrangement, as illustrated in Fig. 1and described above, arranging all of the manually actuatable elementson the instrument board of the vehicle in convenient reach of theoperator. If desired, these various manually controllable elements couldobviously be connected together by suitable means, such as gearing orbelting, so that they would all be'operated simultaneously upon theoperation of one of them, or upon the operation of a master controlelement, so that the various engines could be controlled either inunison or separately. A combined and individual control can also beprovided by connecting all of the governors, or other speed controllingelements of the engine, with a common fiuid reservoir and providingmeans for manually adjusting the pressure'in such a reservoir.

mounted upon the instrument board 62 of the airplane, or other vehicle,and is. supplied with a manually actuable knob 98 screw threaded andlooked upon a sleeve member 92 into which is screw threaded the end of astem 94 which is secured at its opposite end to a piston 96 movable inthe cylindrical reservoir to change the volume' of the fluid spacebetween the piston and the closed end of the cylindrical reservoir.Manual rotation of the knob 98 by screwing the stem 94 in and out movesthe piston 96 to provide the change in volume and consequent change in.the

Such a construction is particularly illustrated in Fig. 2 and in aslightly modified pressure of the hydraulic fluid within the reservoir,the governor cylinders 48, and the tubular connections 88. The sleeve 92is provided, within the cover 98 on the cylinder reservoir 88, with anoutwardly extending flange I which takes the thrust of the piston uponthe screw threaded stem 94. If desired, a dial member I02 may'be securedto the sleeve 92 and provided at itsouter edge with indicia I04 whichcooperate'with similar indicia I06 provided on the edge of the cover 98to indicate .the speed and revolutions per minute of the engines for anyparticular 'setting of the knob 90. Fluid maybe supplied to thereservoir'80 through a suitable fllling spout,

' nism illustrated in Fig. 1.

' speed at which the flyweights -the valve 38 in its neutral position,

' can be attained as indicated at I08, normally closed by a plug H0. Apressure indicating gauge II2 may be connected with the fluid pressurein the system, and this gauge may be calibrated directly in engine speedunits, such as revolutionsper minute. If the calibrated gauge is used,the indicating dial I02 may be omitted, as its purpose will be served bythe indicia on the pressure gauge. The piston 96 in the cylinder 88 maybe provided with a suitable oil, seal, as indicated at H4, and thepiston 50 .in the governor cylinder 48 may be either a lapped piston ormaybe provided with an oil seal IIG. If an oil seal is used on thepiston 50', it may be found desirable to use a coiled compressionspring, as indicated at II8, to relieve the governor from the effects ofany friction produced between surface of the cylinder 48.

Obviously, the operation of the mechanism illustrated in Fig. 2 so fardescribed is substantially the same as the operation of the mecha- Asthe piston 98 is ad justed by turning the hand knob 90, the pressureacting upon the governor pistons 50' is changed, thereby changing theloading on the governor springs 46, which in turn changes the governor32 actto maintain v in which it prevents .the flow of hydraulic fluid toand away from the propeller control mechanism 20.

With a control mechanism as illustrated in Fig. 2, a synchronizingaction upon the engines if the various engine governors 30 arecalibrated to react within permissible limits of each other, since thehydraulic control mechanism will place the same loading upon the springof each of the governors. With this arrangement, if one engine tends tovary its speed with respectyto the other engine, the resultant change inthe governor connected to the engine tending to change its speed willcause a variation in the pressure in the hydraulic system, which willresult in a tendency of the other engines to change their speeds-tomatchthe speed of the particular engine. However, as the governors ofthe other engines will also'afiect the pressure in the system, theresult will be that the governor for the to change its speed will'beadjusted to bring that engine back into synchronism with the speeds ofthe other engines before the speeds of the other engines have varied asubstantial amount from the selected rate. pressure upon .thegovernorslof all the engines, a condition of synchronized engine speedcan be readily maintained with. properly calibrated engine governors.

As, under some circumstances, it may be found desirable, in the ease ofa multi-engined vehicle, to remove one of the engines from the actionofthe combined engine control means, provision this seal and the inner vI28, the plunger I42is the line 88 leading particular engine tendingThus, by maintaining an equal I 3 has been made for connecting anddisconnecting each engine separately with the common reservoir 88. Amechanism suitable for this purpose may include a valve block I20mounted in the instrument .board 62 in convenient reach of the operatorof the vehicle. This block I20 is provided for each engine with oneaperture I24 within which is slidably mounted a valve' stem I28 having aport or reduced portion the adjacent ends of the conduits 88 when thevalve is in the ,open position illustrated in Fig. 2. Each valve iscontrolled by a handle or knob I30 and a latch member I32. The latchmember may ,be provided with catches I34 and I38 located at the open andclosed position of the valve, and is desirably spring pressed in adirection to maintain the latch member in engagement with the edge of aplate I38 secured to'the top of the valve stem, the function of thislatch member being to releasably hold the valve in either its open orclosed position. The valve may be moved upon release of the latchmember. I32 from its open gtO its closed position, or vice versa, bymeans of the hand knob' I30 which is secured to, or made integrallywith, the plate I38. The valve block I20 is provided wit a secondaperture I40 for each engine within which is disposed a plunger I42spring urged downwardly by means of a coiled spring I44 disposed betweena shoulder on the plunger and the under surface oi. the top of a glandnut I46. A screw I48 is screw threaded into the top of the plunger I42and extends upwardly through an aperture in the plate I38 to contactwith the underside of an abutment I50 provided on the stem of the handknob I30. When the knob I30 is pulled outwardly, or upwardly asillustrated in Fig. 1, to close the valve also moved upwardly by contactof the screw head withthe plate I I38. and-draws the hydraulic fluid outof the upper 88 between "the cylinder and valve to relieve the pressureof the hydraulic fluid upon the piston 50'. The purpose of thisarrangement for relieving the pressure in the cylinder of the governoris to permit the propeller to go immediately into its high pitchposition, in case the engine is cut oif because of engine or propellerfailure, or to render the governor subject to separate manual control inthe event it is cut out of the common control mechanism for thatpurpose. If desired, a suitable individual engine control, such as isillustrated in Fig. 1, may also be connected into to each of the enginegovernors in order to provide manual control for each engine at timeswhen combined or unitary engine control is not desirable.

In the form of the invention illustrated in Fig. 4, thegeneralarrangement of parts is similar to that illustrated in Fig. 2, the maindifference being that instead of having a governor spring in eachgovernor, a single spring is provided between the screw threaded stemand the piston disposed within the cylindrical reservoir. Referring par-:ticularly toFig. 4, the governor 30 is provided with a rotatable stemgeared to the engine, and an axiallymovable valve similar to thatillustrated in connection with the governor 30 in Figs. 1 and 2. In thegovernor illustrated in Fig. 4, the flyweights I52 have been illustratedas adjustable so that the governors can be more accurately calibrated.In this construction, the cylinder 48 is similarto the cylinder 48 ofthe governor illustrated in Fig. 1 and receives a lapped piston I54directly connected with a slidable valve I58, and

I28 in line with end of the cylinder and the tubular connection atubular conductor 88 leads from the top of the cylinder 48 through-thecut-out valve I20 which is similar in all respects to that illustratedin Fig. 2 and described above. From this cut-out valve, the conductorleads to the interior of a cylindrical reservoir I58 mounted on theinstrument board 62. The reservoir I58 is provided interiorly thereofwith a reciprocable piston I60, and is closed by a cover member I62, theconduits 88, 88a, 88b, and 880 being led into the closed bottom I 64 ofthe cylinderand opening into the space between the closed bottom and theadjacent end of the piston an upwardly extending annular boss I66provided interiorly thereofwith screw threads into which is threaded amanually rotatable stem I 68 provided with a manually actuatable knobI10. The lower end of the stem I68 is pivotally mounted in an abutmentplate I12 which is slidably, but nonrotatably, received in a cavity I"provided in the inner portion of the boss I66. A coiled compres sionspring I76 is interposed between the abutment I12 and the top of thepiston I68. From this description, it will be observed that the springI16 serves to maintain a selected degree of pressure upon the fluidwithin the reservoir I58, which pressure is transmitted to the pistonsI54 of the various governors and controls the action of the flyweightsso that all of the governors acting against the same pressure will havethe same effect and maintain their respective engines at a constantcommon speed determined by the tension imposed on the spring I16 by themanually adjustable stem I68. The action of the mechanism illustrated inFig. 4 in maintaining the various engines at the same common speed issubstantially the same as that described in connection with Fig. 2.

As stated in connection with the description of Fig. 2, the change inthe action of one governor will result in variation of the pressure ofthe hydraulic fluid, which pressure change will first react uponthegovernors of the other engines to slightly change their speed, andwill then react upon the governors of'all the engines to bring theengine speeds back into synchronism.

While there have been illustrated and described three slightly modifiedarrangements of what is now considered to be the preferred form of theidea of the invention, it is to be understood that the invention is notlimited to the particular construction so illustrated and described butthat such changes in the size, shape, and arrangement engine comprising,

of parts may be resorted to as come within the scope of the sub-joinedclaims.

Having now described the invention so that others skilled in the art mayclearly understand the same, what it is desired to secure by LettersPatent is as follows:

What is claimed is:

1. In combination with a vehicle engine having an engine speedcontrolling'governor thereon, means for manually controlling the speedof said an expansible chamber device in said governor, a manuallyoperable expansible chamber device carried by the vehicle upon whichsaid engine is mounted, and hydraulic conduit means'connecting said twoexpansible chamber devices.

2. In combination with an airplane engine driving a controllable pitchaeronautical propeller, and a governor for controlling the speed of saidengine by changing the pitch of said propeller, means for manuallyadjusting said gov ernor comprising, a piston and cylinder device on I68. The cover I62 isprovided with said governor, a second piston andcylinder device, manually operable means for adjusting the volume ofsaid second piston and cylinder device, and hydraulic conduit meansconnecting said two cylinders.

3. In combination with an airplane engine driving a controllable pitchaeronautical propeller and a governor for controlling the speed of saidengine by changing the pitch of said propeller, a plurality offiyweights in said governor, a spring for opposing centrifugal action ofsaid flyweights, and means governor comprising, a cylinder on saidgovernor, a piston in said cylinder operatively connected with saidgovernor spring to alter the loading thereon, a second cylinder, apiston in said second cylinder, a manually operable screw adjustmentmeans for moving the piston in said second cylinder, and hydraulicconduit means connecting the cylinder on said governor with the cylindercontaining said manually movable piston.

4. In combination with an airplane engine driving a controllable pitchaeronautical propeller and a governor for controlling the speed of saidengine by changing the pitch of said propeller, a plurality offiyweights in said governor, a spring for opposing centrifugal action ofsaid flyweights, and means for manually adjusting said governorcomprising, a cylinder on said governor, a piston in said cylinderoperatively connected with said governor spring to alter the loadingthereon, a second cylinder, a piston in said second cylinder, manuallyoperable means for moving the piston in said second cylinder, hydraulic,conduit means connecting the cylinder on said governor with the cylindercontaining said manually movable piston, and a pressure gauge connectedwith said hydraulic conduit for indicating the pressure in the hydraulicsystem.

5. In combination with an airplane engine driving a controllable pitchaeronautical propeller and a governor for controlling the speed of saidengine by changing the pitch of said propeller, a plurality offlyweights in said governor, a spring for opposing centrifugal action ofsaid flyweights, and means for manually adjusting sald for manuallyadjusting said means connecting the cylinder on said governor with thecylinder containing said manually movable piston, a pressure gaugeconnected with said hydraulic conduit for indicating the pressure in thehydraulic system, and indicia on said pressure gauge reading directly inunits of engine speed.

6. In combination with a plurality of jointly operating engines eachprovided with a speed controlling device, hydraulic means comprising acommon pressure reservoir hydraulically connected with the speedcontrolling device of each engine for maintaining the operating speedsof all of said engines at a common rate.

'7. In combination with operating engines each provided with a speedcontrolling device, hydraulic means comprising a manually adjustableexpansiblechamber reservoir hydraulically connected with each of saidspeed controlling devices for maintaining the operating speed of all ofsaid engines at a common rate and manually selecting such rate.

a 8. In combination with a plurality of jointly a plurality of jointlyally operable .trolling device, hydraulic means comprising a commonpressure reservoir hydraulically con nected with the speed controllingdevices of said engines for maintaining the operating speed oi all ofsaid engines at a common rate, and manumeans for independentlydisconnecting any of said engines from said reservoir.

9. In combination with a plurality of jointly operating engines 'eachhaving a centrifugally actuated speed governor, hydraulic meanscomprising a common pressure reservoir'hydraulically connected with eachof said governors for controlling said governors to maintain saidengines at a common operating speed.

10. In combination with a plurality of jointly operating engines eachhaving a spring controlled centrliugally actuated speed governor,hydraulic means comprising a common pressure reservoir hydraulicallyconnected to each governor to transmit the pressure in said reservoir tothe governor springs, to control said governors to maintain said enginesat a common operating speed.

11. In combination with a plurality of jointly operating engines eachhaving a centrifugally actuated governor provided with a spring, apiston and cylinder on each governor for changing the loading of saidspring, hydraulic means comprising a common variable volumepressurereservoir hydraulicallyconnected with each of said governor cylinders,and means for manually varying the volume of said reservoir.

12. In combination with a plurality of jointly operating engines eachhaving a centrifugally actuated speed governor provided with a pistonand cylinder device for controlling the operation of the governor,hydraulic means comprising a common variable volume reservoirhydraulically connected with the piston and cylinder device of eachgovernor, 'a spring for controlling the pressure of the hydraulicfluidin said reservoir, and manually operable means ior varying theloading on said spring.

13. In an airplane having a plurality of engines each driving acontrollable pitch propeller,

setting, all the engines a centriiugally actuated speed governor on eachengine for controlling the pitch of the respective propeller to maintainthe speed of the engine constant, at a rate consistent with the governormeans for synchronizing the speeds of comprising, a piston and cylinderdevice on each governor for controlling the setting thereoi, and acommon pressure reservoir hydraulically connected with the piston andcylinder device oi each governor for maintaining the settings Mall ofsaid governors the same,

being matched to maintain the at the same speed when the exerted on allthe governor said governors respective engines same pressure is pistons.

14.'In an airplane having a plurality of engines each driving acontrollable pitch propeller, a centrifugally actuated speed governor oneach engine for controlling the pitch oi the respective propeller tomaintain the speed of the engine constant at a rate consistent with thegovernor setting, means for synchronizing the speeds of all the enginescomprising, a piston and cylinder device on each governor forcontrolling the setting thereoi, and a common pressure reservoir thepiston and cylinder device of each'governor for maintaining the settingsof all of said governors the same,

and cylinderdevice of each governor for setting, means for synchronizingthe speeds of all the engines comprising, a piston and cylinder deviceon each governor for controlling the setting thereof, and a commonpressure reservoir hydraulically connected with the piston and cylinderdevice of each governor for maintaining the settings of all of saidgovernors the same, and manually operable means for disconnecting any ofsaid governors from said reservoir.

16. In an' airplane having a plurality of engines each driving acontrollable pitch propeller, a centrifugally actuated speed governor oneach engine for controlling the pitch of the respective propeller tomaintain the speed of the engine constant at a rate consistent with thegovernor setting, means for synchronizing the speeds of all the enginescomprising, a piston and cylinder device on each governor forcontrolling the setting thereof, and a common pressure reservoirhydraulically connected with the piston maintaining the settings of allof said governors .the same, and manually operable connecting any ofsaid governors from said reservoir, and means operatively associatedwith said manually operable means for relieving the pressure of thehydraulic fluid in the piston and cylinder device of a disconnectedgovernor to allow the respective propeller to go to its high pitchcondition or render said governor subject to independent manual control.

1'7. In combination with a mechanism operably connected with acontrollable pitch propeller and a governor for controlling the speed ofsaid mechanism by changingthe pitch of said propeller, means foradjusting said governor means for dis-v comprising, an expansiblechamber device on rality of flyweights, a spring for opposingcentrifugal action of said flywheights, and means for manually adjustingthe force of said spring comprising an expansible chamber deviceoperatively connected with said governor spring to alter the loadingthereon and thereby change the governed speed, means for operating saidexpansible chamber device in both directions, said last named meanscomprising a control device and hydraulic conduit means connecting saidexpansible chamber device and said control device.

19. In combination with a prime mover having a speed controllinggovernor constructed and arranged to control the speed of said primemover, means for adjusting said governor to vary the controlled speed,said governor and said by centrifugal force, and means for manuallyadurging said device in one direction, and means justing the force ofsaid spring, said last named for introducing hydraulic fluid to saidexpansible means comprising an expansible chamber device chamber devicefor urging said device in the operatively connected with said governorspring other direction, and means vfor controlling the to alter theloading thereon and thereby change flow of hydraulic fluid to and fromsaid expan- 5 the governed speed, means for operating said sible chamberdevice.

expansible chamber device in two directions, said ERLE MARTIN. lastnamed means comprising resilient means JOHN ELMER ANDERSON.

